This invention is related to the manufacture of semiconductor chips. In particular, it is an apparatus for cleaning a nozzle used in spraying developer on a wafer that is being processed.
The manufacture of semiconductor chips is carried out by securing a wafer of silicon or the like on a vacuum chuck that holds the wafer while it is being processed. The processes that are performed include placing a resist, placing a pattern on the resist by photolithography or the use of an imaging stepper to expose the resist, and developing the pattern. The wafer is moved from place to place for each stage of processing by some automatic means such as a controlled robot. At certain stages, the processing liquids are sprayed onto the wafer by an appropriate nozzle. The developer is typically sprayed through a commercially available nozzle referred to as an E-squared nozzle. An E-squared nozzle has a number of holes in a line that is approximately equal in length to the radius of a wafer. This radius may be four, six, or eight inches, although other dimensions may be used.
Sometimes developer hardens in one or more nozzles. When this happens, the nozzle deposits developer unevenly on the wafer, resulting in defective chips. This leads to scrap and to downtime while the nozzle is cleaned. Hardening of the developer is least likely to happen when the nozzle is in continual use, and it is most likely to happen when the line is shut down for some reason or when a particular process does not call for the application of developer for a time. It would increase production of semiconductor chips, improve quality of the chips produced, and reduce scrap if the E-squared nozzle in a developer station could be kept free of hardened developer.